It is previously known in the art to have semiautomatic pneumatic guns. In such guns, each pull of the trigger causes the release of compressed gas to propel a projectile from the gun. In a true semiautomatic, compressed gas also provides the motive force to return the gun to the cocked state.
In common with manually cocked guns, semiautomatics in general incorporate a gun frame, a grip, a barrel, a projectile chamber at a breech end of the barrel, a magazine of projectiles with a feed assembly for successively introducing individual projectiles into the projectile chamber, a mechanism to prevent the projectile then in the chamber from rolling forward when the gun in tilted downward, an operator actuatable trigger mechanism, a source of compressed gas, and an internal gas reservoir having at least one normally closed valve which opens briefly in response to trigger actuation, thereby releasing compressed gas to propel the projectile then in the projectile chamber from the gun.
Some mechanism for sealing the projectile chamber against loss of the compressed gas released to propel the projectile will also generally be present in the gun. Typical sealing mechanisms are a longitudinally slidable bolt, a rotatable bolt, a transversely slidable clip, a slide, or a slidable barrel.
It is common in a semiautomatic pneumatic gun as shown in my U.S. Pat. No. 5,063,905 for the valve opening and release of compressed gas upon firing to be effected by the impact of a striker. In such a gun, the striker is restrained in a cocked position against the urging of a compressed striker power spring by a sear in the trigger mechanism. Trigger actuation withdraws the sear, releasing the striker to impact upon and briefly open one or more normally closed main valves. Gas released by the opening of the main valve or valves acts to propel the projectile then within the projectile chamber from the gun, and by virtue of a piston and cylinder mechanism which forms a recock chamber, to return the gun to the cocked state. A movable portion of the piston and cylinder mechanism may serve as the striker, or this movable portion may be linked to a separate striker.
Efficient utilization of the energy available from the compressed gas provided to the gun is advantageous to the user. Achieving efficiency imposes two generally opposed requirements on the mechanism used to achieve the recock-motion and main valve impact functions. First, the recock motion function is ideally achieved if the recock chamber is substantially sealed against the loss of compressed gas from the time the gas is introduced until the recock motion is completed. Second, the impact function is ideally achieved if striker motion from the cocked position to the position of impact is not impeded by the compression of residual gas within the chamber.
Mechanical simplicity is also a desirable goal in the design and manufacture of a compressed gas gun. Most prior art guns employ separate a barrel, hammer, and main valve. In addition, in semiautomatic guns in which gas pressure is utilized to recock the gun automatically, the hammer or striker and bolt are typically interconnected so as to move together thus increasing the friction generated within the gun. To reduce the mechanical complexity of gas-powered guns, it is known to utilize the barrel itself as a striker or hammer by providing a movable barrel which actuates the main valve when the trigger is depressed. U.S. Pat. No. 4,147,152 to Fischer et al., U.S. Pat. No. 4,531,503 to Shepherd, and U.S. Pat. No. 3,204,625 to Shepherd all describe gas-pressurized guns utilizing a moving barrel with the striker or hammer on the main valve. However, the incorporation of a true semiautomatic operation eluded the inventors of these devices. U.S. Pat. No. 2,817,328 to Gale is one example of a reciprocating barrel, semiautomatic compressed-gas gun. However, although this gun achieves semiautomatic operation in a reciprocating barrel gun, Gale forfeits use of the barrel itself as a striker or hammer thus reverting to a more complex mechanical structure while attempting to obtain the benefits of a mechanically less complex sliding barrel gun. Thus, a need exists for a reciprocating barrel/striker-fired pneumatic gun having a minimum number of moving parts which effectively utilizes the mechanical simplicity of a reciprocating barrel design while providing true semiautomatic operation.